CO_2跨临界水——水热泵循环系统的实验研究

在作者设计和建立的实验台上进行了CO2 跨临界水—水热泵多种工况的循环性能实验研究 ,系统运行稳定、调节方便。实验结果表明 ,系统运行时的最大制冷 (热 )系数取决于系统的蒸发温度和气体冷却器出口温度。CO2 跨临界循环热泵较之传统工质热泵具有较大优势 ,尤其是在高温热泵领域。指出了系统的改善措施     

CO2跨临界水-水热泵供热系统应用理论探讨

运用当量温度概念对CO2跨临界水-水热泵供热系统进行了研究,指出根据实际情况选择气体冷却器的出口温度和压缩机的出口压力能提高系统的运行效率,并对供热过程中采用能量梯级利用进行了研究,结果表明对热水侧进行梯级利用可提高系统的制热性能系数.     

带膨胀机CO2跨临界热泵系统运行特性

建立了带膨胀机CO2跨临界热泵系统的数学模型,将模拟计算结果与实验测量结果进行了比较,验证了模型的准确性。利用数学模型分析了冷却水进口温度和质量流量、冷冻水进口温度和质量流量对带膨胀机CO2跨临界热泵系统的制冷性能系数及最佳高压侧压力的影响。降低冷却水进口温度和提高其质量流量不仅有利于提高制冷性能系数,而且能降低最佳高压侧压力。提高冷冻水进口温度及质量流量有利于提高制冷性能系数,对最佳高压侧压力影响不大。     

CO2跨临界循环和除湿法冷却联合循环系统的研究

为有效回收和利用CO2跨临界循环的气体冷却器排气热量，提出了一种将除湿法冷却供冷和CO2跨临界循环结合起来的系统方式，介绍了系统的组成和特点，分析了系统的循环效率、可行性和经济性，指出该方式可有效提高系统的综合能源利用效率，并可满足全年的空调要求。     

CO2跨临界水源热泵两级供热系统理论比较

在供热系统中，需要的水温较高时，由于回水温度高而导致CO2跨临界水源热泵能效比下降。如果降低回不温度，就要求不同温度的热水分级处理。CO2跨临界水源热泵两级供热系统可以实现能量的分级利用。分析对比了3种形工的CO2跨临界水源热泵两级供热系统，发现它们各有特点，可根据不同的使用要求采用适宜的两组系统。     

跨临界CO2热泵系统电子膨胀阀控制方法研究

本文分别采用PID控制和模糊控制两种方法对跨临界CO2热泵系统的电子膨胀阀进行控制,控制过程均通过将蒸发器过热度作为被控量来控制阀门开度的方法来实现对R系列的电子膨胀阀进行控制。通过使用Simulink建立PID控制和模糊控制的模型并进行模拟,并对这两种控制方法进行对比,可以看出使用模糊控制方法时蒸发器的过热度响应时间更快,且过热度在控制过程中变化更为平稳,因此得出模糊控制方法更加适用于对跨临界CO2热泵这种具有强烈非线性特性的系统进行控制的结论。     

跨临界CO2汽车空调系统研究进展

综述了近年来这种空调系统在理论和实验研究方面取得的主要进展,包括系统各主要部件(压缩机、换热器和节流机构)的发展状况及研究的发展趋向。已有的研究表明,系统的COP存在最大值,而且与气体冷却器出口温度几乎呈正比关系;气体冷却器的出口温度和压缩机的效率是影响系统性能的主要因素;安装内部换热器可以提高系统的性能,尤其是在高压侧压力不高时;当高压侧压力较高时,与气体冷却器和压缩机相比,吸气换热器的影响几乎可以忽略不计。     

太阳能冷管和跨临界CO2热泵联合供能设计

本文设计了一个由太阳能冷管和跨临界CO2热泵组成的联合供能系统,可以实现制冷+供热水、制热+供热水、单独制冷、单独制热、单独供热水的功能。夏天用太阳能冷管制冷并提供生活热水,当太阳能不足或阴雨天气时,由跨临界CO2系统替代;冬天用跨临界CO2热泵制热并提供热水;过渡季节晴天时由太阳能冷管提供热水,阴雨天气时由跨临界CO2系统替代。这是一种将太阳能冷管吸附式制冷技术和跨临界CO2热泵技术联合的可实现制冷、制热和供热水功能的联合系统,集空调热泵和热水器于一体,是一个利用新能源、环保节能的紧凑型系统。     

跨临界CO2热泵中蒸发器的数值模拟

运用CFD数值模拟的方法,通过编写自定义函数来设置气液质量转移源项、能量源项和管外壁温度边界条件,对简化后的跨临界CO2热泵热水器中蒸发器进行了数值模拟,得到了管内二氧化碳的温度场、压力场和气液相分布。模拟结果表明：CO2流体在进入弯管前已出现干涸现象,但进入弯管后干涸现象消失,液相气化速度变缓,出弯后重新恢复正常气化过程;CO2在管上部的气化速度要大于管下部,同时由于管壁换热作用,管四周的气化速度要大于管中心位置。     

CO2跨临界循环中气体冷却器的熵产分析

指出CO2跨临界制冷循环中的放热设备是气体冷却器,CO2在整个放热中并无相变,其状态主要是超临界流体,针对超临界流体的特殊性质,用熵产分析研究气体冷却器的换热问题;在此基础上,提出了气体冷却器优化设计的原则与方法。     

机械驱动水—水热泵系统的实验研究

研制了机械驱动水－水热泵实验装置。实验研究揭示：转速变化会导致系统性能变化；系统的EER特性在转速变化范围内有极值，所以系统的额定工况可选定在该转速下；系统的制热量变化幅度大，能在额定工况上下调节；采用混合换热器回收发动机余热和尾气废热，能使局部流量范围的出水温度达到95℃。对燃用天然气的内燃机驱动水－水热泵系统与电动热泵系统的能源消耗作经济比较，得出了可用于判断其应用前景的能源消耗准则。     

Control of CO2 in a naturally ventilated classroom

The ventilation performance of a naturally ventilated classroom was investigated to monitor the CO₂ levels and compare compliance with new guidelines. Measurements of CO₂ levels were taken for 1 week during the heating season while different ventilation modes were investigated.     

HVAC system optimization with CO2 concentration control using genetic algorithms

This study describes the use of genetic algorithms (GAs) for operating standard HVAC systems (HVAC—heating, ventilation and air conditioning) in order to optimize performance, primarily with regard to power saving. Genetic algorithms were introduced as an instrument for solving optimization problems. Analytic optimization procedures are widely used in other fields of engineering, but they are difficult to operate within HVAC systems, because the range of the research is usually too broad, the problems are not linear but rather discontinuous, and they mostly have complex limitations. This is why for this type of system genetic algorithms are used, since they have the qualities of robustness and efficiency that are crucial for finding the optimal solution. A simulation is conducted in order to demonstrate how much power can be saved by using the suggested method of CO₂ concentration control in a standard HVAC system. In addition to Matlab Simulink, the suggested method is verified with Energy software.     

溶剂吸收法CO2捕集技术简述

CO2捕集是温室气体减排与利用的重要技术步骤之一。文章介绍了CO2捕集的气源及特点、捕集溶剂与填料的研究进展、能量集成和工艺优化以及化工流程模拟研究,提出该技术研究的重点与方向。     

Monitoring off-gas O2/CO2 to predict nitrification performance in activated sludge processes

Nitrification/denitrification (NDN) processes are the most widely used technique to remove nitrogenous pollutants from municipal wastewater. The performance of nitrogen removal in the NDN process depends on the metabolism of nitrifying bacteria, and is dependent on adequate oxygen supply. Off-gas testing is a convenient and popular method for measuring oxygen transfer efficiency (OTE) under process conditions and can be performed in real-time. Since carbon dioxide is produced by carbonaceous oxidizing organism and not by nitrifiers, it should be possible to use the off-gas carbon dioxide mole fraction to estimate nitrification performance independently of the oxygen uptake rate (OUR) or OTE. This paper used off-gas data with a dynamic model to estimate nitrifying efficiency for various activated sludge process conditions. The relationship among nitrification, oxygen transfer, carbon dioxide production, and pH change was investigated. Experimental results of an online off-gas monitoring for a full-scale treatment plant were used to validate the model. The results showed measurable differences in OUR and carbon dioxide transfer rate (CTR) and the simulations successfully predicted the effluent ammonia by using the measured CO₂ and O₂ contents in off-gas as input signal. Carbon dioxide in the off-gas could be a useful technique to control aeration and to monitor nitrification rate.     

混合工质在地热热泵系统中的实验研究

针对以40－45℃地热尾水为低温热源的热泵系统，作了大量的实验研究。首先，在该系统中采用了循环性能较好的低环害混合工质，以达到实际运行和环保要求；其次，根据不同的冷凝器水流量和进口水温，总结得出了大量稳定工况实际样本，绘制了不同流量和水温下的COP值曲面，为热泵在实际工程应用中的变工况调节运行智能化提供了理论依据。     

建筑材料全寿命期CO2 排放量计算方法

建筑材料CO2 减排是我国整体CO2 减量计划的重要方面,建筑材料CO2 排放量的计算是发展低碳建材、推进建筑节能减排的前提和基础,为此需要确立建筑材料CO2 排放量的计算方法。通过CO2 排放活动分析,从全寿命期和CO2 排放源角度,确定了建筑材料CO2 排放构成;并对六种建筑材料CO2 排放量的计算方法进行了比较分析,选择碳排放系数法作为计算我国建筑材料CO2 排放量的方法;构建了建筑材料全寿命期CO2 排放三阶段计算模型,并提出了建筑材料生产、运输以及处置阶段CO2 排放因子的确定方法。应用实例显示,该方法可较方便地测算出建筑材料全寿命期CO2 排放量。     

Effect of green roof on ambient CO2 concentration

Plants can improve air quality by removing pollutants. The air purification capability of plants has been receiving increasing attention because of the rapid deterioration of the environment. However, research on evaluating quantitatively the effect of plants on the environmental pollutant concentrations is still scarce. This paper studies the effect of a green roof on the ambient CO₂ concentration as an example to assess the benefit of urban greening. The study comprises three parts: (1) Field measurement of the difference of CO₂ concentration at a location in the middle of the plants in a small plot of green roof and one in the surrounding area, (2) Experiments to measure the plant’s CO₂ absorption velocity and emission rate using a sealed glass chamber; and (3) Computer simulation of the CO₂ concentration distribution around a green roof using the measured CO₂ absorption velocity and emission rate to quantify the effects of the green roof on the ambient CO₂ concentration.     

Uncertainties associated with global effects of atmospheric CO2

Although the evidence is quite clear that the increase in atmospheric CO₂ is at least to a large degree a result of fossil fuel burning, and it is equally clear that this increase will result in some change in the global climate, there are quantitative uncertainties that require additional understanding before full assessments can be made. There are quantitative uncertainties in the natural carbon cycle as well as uncertainties in the behaviour of the various reservoirs when perturbed by man. There are questions about the terrestrial biosphere and about the rate at which the oceans can assimilate and store carbon.There are uncertainties in regard to the climate change that can result from increased atmospheric CO₂. Progress in modelling the atmosphere must continue to narrow these uncertainties before the impacts of climate change on man can be adequately determined.The future demands for fossil fuels are uncertain. The growth of the developing world will be closely linked to fossil energy for the next five to eight decades, and rates of growth in these world segments are dependent on many ill-defined quantities.Only the observed increase in the atmospheric concentration and the present (and recent past) rate of production of CO₂ from fossil fuels provide data without uncertainties.